Extensible implantable medical lead with braided conductors

ABSTRACT

An extensible implantable electrical lead includes a lead body having a proximal end and a distal end. The lead body is formed of a polymeric material that is extensible between a first length and a second length. A plurality of electrical conductors are disposed within the lead body and extend between the proximal end and the distal end. The plurality of electrical conductors are each electrically insulated from each other and form a braided coil extending between the proximal end and the distal end. The plurality of electrical conductors are electrically insulated and separated from each other and have a braided coil diameter.

FIELD

The present disclosure relates to extensible implantable medical leadswith braided conductors.

BACKGROUND

Implantable medical devices are commonly used today to treat patientssuffering from various ailments. Such implantable devices may beutilized to treat conditions such as pain, incontinence, sleepdisorders, and movement disorders such as Parkinson's disease andepilepsy, for example. Such therapies also appear promising in thetreatment of a variety of psychological, emotional, and otherphysiological conditions.

One known type of implantable medical device, a neurostimulator,delivers mild electrical impulses to neural tissue using an electricallead. For example, to treat pain, electrical impulses may be directed tospecific sites. Such neurostimulation may result in effective painrelief and a reduction in the use of pain medications and/or repeatsurgeries.

Typically, such devices are totally implantable and may be controlled bya physician or a patient through the use of an external programmer.Current systems generally include a primary cell neurostimulator, a leadextension, and a stimulation lead, and two particular applications ofsystems may be referred to as: (1) spinal cord stimulation; and (2) deepbrain stimulation.

A spinal cord stimulator may be implanted in the abdomen, upper buttock,or pectoral region of a patient and may include at least one extensionrunning from the neurostimulator to the lead or leads which are placedsomewhere along the spinal cord. Each of the leads (to be discussed indetail hereinafter) often includes from one to sixteen, or moreelectrodes. Each extension (likewise to be discussed in detail belowhereinafter) is plugged into or connected to the neurostimulator at aproximal end thereof and is coupled to and interfaces with the lead orleads at a distal end of the extension or extensions.

The implanted neurostimulation system is configured to send mildelectrical pulses to the spinal cord. These electrical pulses aredelivered through the lead or leads to regions near the spinal cord orthe nerve selected for stimulation. Each lead includes a small insulatedwire coupled to an electrode at the distal end thereof through which theelectrical stimulation is delivered. The lead may also include acorresponding number of internal wires to provide separate electricalconnection to each electrode such that each electrode may be selectivelyused to provide stimulation. Connection of the lead to an extension maybe accomplished by means of a connector block including, for example, aseries or combination of set-screws, ball-seals, etc. The leads areinserted into metal set screw blocks, and metal set screws aremanipulated to press the contacts against the blocks to clamp them inplace and provide an electrical connection between the lead wires andthe blocks.

A deep brain stimulation system includes similar components (i.e. aneurostimulator, at least one extension, and at least one stimulationlead) and may be utilized to provide a variety of different types ofelectrical stimulation to reduce the occurrence or effects ofParkinson's disease, epileptic seizures, or other undesirableneurological events. In this case, the neurostimulator may be implantedinto the pectoral region of the patient. The extension or extensions mayextend up through the patient's neck, and the leads/electrodes areimplanted in the brain. The leads may interface with the extension justabove the ear on both sides of the patient. The distal end of the leadmay contain from four to sixteen, or more electrodes and, as was thecase previously, the proximal end of the lead may connect to the distalend of the extension and held in place by set screws. The proximalportion of the extension plugs into the connector block of theneurostimulator.

Both of the spinal cord stimulation and deep brain stimulation implantedsystems traverse portions of the human body that stretch and relax. Toaccount for this stretching and relaxing, the lead and lead extensioncan be looped to allow for stretching and relaxing with the human body.

BRIEF SUMMARY

The present disclosure relates to extensible implantable medical leadswith braided conductors.

In an exemplary embodiment, an extensible implantable electrical leadincludes a lead body having a proximal end and a distal end. The leadbody is formed of a polymeric material that is extensible between afirst length and a second length. A plurality of electrical conductorsare disposed within the lead body and extend between the proximal endand the distal end. The plurality of electrical conductors are eachelectrically insulated from each other and form a braided coil extendingbetween the proximal end and the distal end. The plurality of electricalconductors are electrically insulated and separated from each other andhave a braided coil diameter.

In another exemplary embodiment, an implantable neurostimulation systemincludes a neurostimulating device and an extensible electrical lead,described herein, electrically coupled to the neurostimulating device.

In another exemplary embodiment, a method includes applying a force of 5N or less to a proximal end and a distal end of an extensible electricallead having a first length. The force increases the first length of theextensible electrical lead by at least 10%. Then the force is removedfrom the extensible electrical lead to return the extensible electricallead to its first length.

BRIEF DESCRIPTION OF THE DRAWING

The disclosure may be more completely understood in consideration of thefollowing detailed description of various embodiments of the disclosurein connection with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a spinal cord stimulation systemimplanted within a human body;

FIG. 2 is a schematic diagram of a deep brain stimulation systemimplanted within a human body;

FIG. 3 is a schematic exploded view of an implantable active medicaldevice;

FIG. 4 is a schematic partial cross-sectional diagram of an exemplaryextensible lead taken along line 4-4 of FIG. 3;

FIG. 5 is a schematic diagram of the extensible lead in a stretchedstate and a relaxed state; and

FIG. 6 is a schematic cross-sectional diagram of an exemplary extensiblelead taken along line 6-6 of FIG. 3.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

-   -   In the following description, reference is made to the        accompanying drawings that form a part hereof, and in which are        shown by way of illustration several specific embodiments. It is        to be understood that other embodiments are contemplated and may        be made without departing from the scope or spirit of the        present disclosure. The following detailed description,        therefore, is not to be taken in a limiting sense.

All scientific and technical terms used herein have meanings commonlyused in the art unless otherwise specified. The definitions providedherein are to facilitate understanding of certain terms used frequentlyherein and are not meant to limit the scope of the present disclosure.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein.

The term “lead” refers to either or both a lead and a lead extension asdescribed below, unless otherwise noted.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, and 5) and any range within that range.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

The term “active implantable medical device” or “implantable signalgenerator” are used interchangeably and includes, for example, a cardiacpacemaker, an implantable defibrillator, a congestive heart failuredevice, a hearing implant, a cochlear implant, a neurostimulator, a drugpump, a ventricular assist device, an insulin pump, a spinal cordstimulator, an implantable sensing system, a deep brain stimulator, anartificial heart, an incontinence device, a vagus nerve stimulator, abone growth stimulator, a gastric pacemaker, and the like.

The present disclosure relates to extensible implantable medical leadswith braided conductors where the lead or lead extension is extensiblebetween a stretched state and a relaxed state. These extensible leadsare particularly useful as implantable leads for neurostimulatorapplications where the leads provide spinal cord stimulation and deepbrain stimulation and traverse portions of the human body that stretchand relax, though the leads are not limited to such applications. Toaccount for this stretching and relaxing within the patient, the lead isrepeatedly extensible. The extensible leads described herein are formedby at least a plurality of electrical conductors that are separated andinsulated from each other and form a braided coil between a proximal endand a distal end of the extensible lead. The braided conductor coil isdisposed within a stretchable or extensible outer sheath that has anextensibility of at least 10% or at least 20% or at least 25%, or more.Thus, the extensible lead can be stretched by at least 10% or at least20% or at least 25%, or more (when exposed to a force of 5 N or less)and return to its original length when relaxed. While the presentdisclosure is not so limited, an appreciation of various aspects of thedisclosure will be gained through a discussion of the examples providedbelow.

FIG. 1 is a schematic diagram of a spinal cord stimulation systemimplanted within a human body or patient 28. The implanted spinal cordstimulation system includes an active medical device 20 such as aneurostimulator. The active medical device 20 is coupled to a leadextension 22 having a proximal end coupled to the active medical device20, and a lead 24 having a proximal end coupled to a distal end or leadconnector 32 of the lead extension 22 and a distal end of the lead 24coupled to one or more electrodes 26.

In some embodiments, the lead 24 proximal end is coupled to the activemedical device 20, without a need for the lead extension 22. The spinalcord neurostimulator 20 is illustrated being implanted within the torsoor abdomen of the patient or human body 28. The lead 24 is shown placedsomewhere along the spinal cord 30. In many embodiments, the activemedical device 20 has one or two leads 24 each having four to sixteen,or more, electrodes.

Such a system may also include a physician programmer and a patientprogrammer (not shown). The active medical device 20 can be consideredto be an implantable signal generator of the type available fromMedtronic, Inc., and capable of generating multiple signals occurringeither simultaneously or one signal shifting in time with respect to theother, and having independently varying amplitudes and signal widths.The active medical device 20 contains a power source and the electronicsfor sending precise, electrical signals to the patient to provide thedesired treatment therapy. While the active medical device 20, in manyembodiments, provides electrical stimulation by way of signals, otherforms of stimulation may be used as continuous electrical stimulation.

FIG. 2 is a schematic diagram of a deep brain stimulation systemimplanted within a patient or human body 28. The implanted deep brainstimulation system includes an active medical device 20 such as aneurostimulator. The active medical device 20 is coupled to a leadextension 22 having a proximal end coupled to the active medical device20, and a lead 24 having a proximal end coupled to a distal end or leadconnector 32 of the lead extension 22 and a distal end of the lead 24coupled to one or more electrodes 26.

In some embodiments, the lead 24 proximal end is coupled to the activemedical device 20, without a need for the lead extension 22. The deepbrain neurostimulator 20 is illustrated being implanted within thepectoral region of the patient or human body 28. The lead 24 is shownplaced somewhere on or within the brain. In many embodiments, the activemedical device 20 has one or two leads 24 each having four to sixteen,or more, electrodes.

Such a system may also include a physician programmer and a patientprogrammer (not shown). The active medical device 20 can be consideredto be an implantable signal generator of the type available fromMedtronic, Inc. and capable of generating multiple signals occurringeither simultaneously or one signal shifting in time with respect to theother, and having independently varying amplitudes and signal widths.The active medical device 20 contains a power source and the electronicsfor sending precise, electrical signals to the patient to provide thedesired treatment therapy. While the active medical device 20, in manyembodiments, provides electrical stimulation by way of signals, otherforms of stimulation may be used as continuous electrical stimulation.

FIG. 3 is a schematic exploded view of the implantable stimulationsystem described above that includes an exemplary lead extension 22configured to be physically and electrically coupled between aneurostimulator 20 and lead 24. The implantable stimulation systemdescribed herein allows individual contacts 26 at the distal end of thelead 24 to be addressed individually by the neurostimulator 20 via theindividual insulated electrical conductor extending through the lead 24as described below.

A proximal portion of the lead extension 22 includes a connector 23configured to be received or plugged into connector block 21 ofneurostimulator 20. A distal end of the lead extension 22 includes alead connector 32 including internal contacts configured to receive aproximal end of the lead 24 having contacts 25 thereon.

The lead 24 includes a plurality of insulated electrical conductors eachcoupled at their proximal end to a lead connector 32 via contacts 25 atits proximal end and to contacts/electrodes 26 at its distal end. Someleads are designed to be inserted into a patient percutaneously and someare designed to be surgically implanted. In some embodiments, the lead24 may include a paddle (not shown) at its distant end for housingelectrodes 26. In some embodiments, electrodes 26 may include one ormore ring contacts at the distal end of lead 24. Each contact iselectrically coupled to a single insulated electrical conductorextending through the lead 24 as described below.

The lead 24 and/or lead extension 22 has a body formed of an extensiblepolymeric material that allows the lead 24 and/or lead extension 22 tostretch and relax at least 10%, or least 20%, or at least 25%, or atleast 50%, as illustrated in FIG. 5 and return to its original orrelaxed length L. In some exemplary embodiments, the extensiblepolymeric material is silicone and the insulated electrical conductorare configured to allow the lead 24 and/or lead extension 22 to stretchand relax at least 10%, or least 20%, or at least 25%, or at least 50%,as illustrated in FIG. 5. The extensibility values reported herein arebased on an applied force of 5 N or less.

FIG. 4 is a schematic partial cross-sectional diagram of the extensiblelead taken along line 4-4 of FIG. 3. FIG. 5 is a schematic diagram ofthe extensible lead in a stretched state and a relaxed state. Theextensible lead includes a lead body 40 extending between a proximal end42 and a distal end 41. FIG. 6 is a schematic cross-sectional diagram ofthe extensible lead taken along line 6-6 of FIG. 3.

The lead body 40 is formed of a polymeric material that is extensiblebetween a first length L and a second length L+ΔL, where the secondlength is greater than the first length by at least 10%, or least 20%,or at least 25%, or at least 50%. This increase in length isaccomplished by application of a force of 5 N or less. Upon removal ofthe force, the lead body 40 relaxes, contracts, or returns to itsoriginal length L. The lead body 40 can be cycled between the firstlength and the second length thousands of times or more.

The lead body 40 can include an outer sheath 43 surrounding the braidedcoil 50. In many exemplary embodiments, the lead body 40 includes aninner sheath 60 disposed within the lumen of the braided coil 50. FIG. 6illustrated the configuration of the outer sheath 43, the braided coil50 and the inner sheath 60 all in co-axial relation to each other. Aninner lumen 44 can form a void or be filled with an extensible polymericmaterial.

In some exemplary embodiments, the outer sheath 43, braided coil 50, andinner sheath 60 are fixed at the proximal end 42 and a distal end 41 ofthe lead body 40. In many embodiments the outer sheath 43 (andoptionally inner sheath 60) is loosely disposed about or within thebraided coil 50 between the proximal end 42 and a distal end 41 of thelead body 40.

In many embodiments, the extensibility of the sheaths 43, 60substantially match the stretchability of the braided coil 50. Thesheaths 43, 60 are formed of an extensible polymeric material thatallows the lead body 40 to stretch and relax at least 10%, or least 20%,or at least 25%, or at least 50%, as illustrated in FIG. 5. In manyembodiments, the extensible polymeric material is silicone and theinsulated electrical conductors are configured to allow the lead body 40to stretch and relax at least 10%, or least 20%, or at least 25%, or atleast 50%, as illustrated in FIG. 5. The inner sheath 60 and or outersheath 43 can assist in the returning the braided coil 50 to its relaxed(larger diameter) state after the braided coil 50 has been stretched (toa smaller diameter). Thus, the braided coil 50 can operate in a mannersimilar to devices known as a “finger trap” where pulling on the ends ofthe braided coil 50 causes the coil to decrease in diameter and thenpushing on the ends of the braided coil 50 causes the coil to increasein diameter.

A plurality of electrical conductors 51 ₁, 51 ₂, 51 ₃, 51 ₄, 52 ₁, 52 ₂,52 ₃, 52 ₄ are disposed within the lead body 40 and extending betweenthe proximal end and the distal end of the lead body 40. The pluralityof electrical conductors 51 ₁, 51 ₂, 51 ₃, 51 ₄, 52 ₁, 52 ₂, 52 ₃, 52 ₄are each electrically insulated from each other and form a braided coil50 from the proximal end to the distal end.

The braided coil 50 can have any useful diameter such as, for example,from 1800 to 2500 micrometers. The braided coil 50 is formed by windingand braiding the individual insulated conductors 51 ₁, 51 ₂, 51 ₃, 51 ₄,52 ₁, 52 ₂, 52 ₃, 52 ₄. A plurality of these conductors are wound in afirst direction (e.g., clockwise) and braided with the remainingconductors that are wound in a second direction opposing the firstdirection (e.g., counter clockwise). FIG. 4 illustrates each braidmember including two parallel wound and separated individual insulatedconductors, however each braid member can include just a singleseparated individual insulated conductor or more than two parallel woundseparated individual insulated conductors, as desired.

In the exemplary embodiment illustrated, a first braid member include afirst two parallel wound separated individual insulated conductors 51 ₁,51 ₂ and a second braid member is parallel wound and includes a secondtwo parallel wound separated individual insulated conductors 51 ₃, 51 ₄.A third and fourth braid member is wound in an opposing direction to thewinding direction of the first and second braid members. The third braidmember include a third two parallel wound separated individual insulatedconductors 52 ₁, 52 ₂ and a fourth braid member is parallel wound andincludes a fourth two parallel wound separated individual insulatedconductors 52 ₃, 52 ₄.

While the illustrated embodiment includes four braid members where eachbraid includes 2 insulated electrical conductors equaling a total ofeight insulated electrical conductors, the braided coil can include anyuseful number of insulated electrical conductors such as, for example,from 3 to 16, or from 4 to 16, or from 4 to 16, as desired.

The insulated conductors described above that form the braided coil 50can have any useful diameter and the braided coil 50 can have any usefuldiameter such as, for example 0.5 to 3 millimeters, or from 0.5 to 2millimeters, or from 0.5 to 1 millimeter. In some exemplary embodiments,the electrical conductors have a diameter or thickness in a range from50 to 250 micrometers, or from 100 to 150 micrometers and the insulatorlayer can add from 15 to 50 micrometers to the electrical conductordiameter or thickness. Thus, in many embodiments, the insulatedelectrical conductors have a diameter or thickness in a range from 65 to300 micrometers, or from 115 to 200 micrometers. The insulator layer canbe formed of any useful electrically insulating material such as, forexample, a polymeric material. In some embodiments, the electricallyinsulating material includes silicone.

In many embodiments, the electrical conductors and/or the insulatedelectrical conductors 51 ₁, 51 ₂, 51 ₃, 51 ₄, 52 ₁, 52 ₂, 52 ₃, 52 ₄used to form the braided coil 50 have the same or substantially the samediameter or thickness. In many embodiments, the insulated electricalconductors 51 ₁, 51 ₂, 51 ₃, 51 ₄, 52 ₁, 52 ₂, 52 ₃, 52 ₄ have acircular cross-sectional profile, however in some embodiments, theinsulated electrical conductors 51 ₁, 51 ₂, 51 ₃, 51 ₄, 52 ₁, 52 ₂, 52₃, 52 ₄ have a rectangular cross-sectional profile. In these embodimentsthe insulated electrical conductors can have an aspect ratio(thickness:width) in a range from 1:1 to 1:20 or from 1:2 to 1:10.

The lead body 40 extends between a proximal end 42 and a distal end 41.As shown in FIG. 3 and FIG. 5, stimulating electrodes 26 are located atthe distal end 41 and contacts 25 are located at the proximal end 42.Each insulated electrical conductor 51 ₁, 51 ₂, 51 ₃, 51 ₄, 52 ₁, 52 ₂,52 ₃, 52 ₄ used to form the braided coil 50 can be addressed between asingle contact 25 and a single electrode 26 such that each electrode 26can be individually activated via the contact and a single insulatedelectrical conductor.

Thus, exemplary embodiments of the EXTENSIBLE IMPLANTABLE MEDICAL LEADWITH BRAIDED CONDUCTORS are disclosed. One skilled in the art willappreciate that the present disclosure can be practiced with otherembodiments. The disclosed embodiments are presented for purposes ofillustration and not limitation, and the present disclosure is limitedonly by the claims that follow.

1. An extensible implantable electrical lead comprising: a lead bodyhaving a proximal end and a distal end, the lead body formed of apolymeric material that is extensible between a first length and asecond length, the second length being 10% greater than the firstlength; and a plurality of electrical conductors disposed within thelead body and extending between the proximal end and the distal end, theplurality of electrical conductors are each electrically insulated fromeach other and form a braided coil extending between the proximal endand the distal end, the plurality of electrical conductors areelectrically insulated and separated from each other and have a firstbraided coil diameter and a second length braided coil diameter beingless than the first length braided coil diameter.
 2. An extensibleimplantable electrical lead according to claim 1, wherein the pluralityof insulated electrical conductors each have substantially the sameouter diameter.
 3. An extensible implantable electrical lead accordingto claim 1, wherein the second length is at least 20% greater than thefirst length.
 4. An extensible implantable electrical lead according toclaim 1, wherein the second length is at least 25% greater than thefirst length.
 5. An extensible implantable electrical lead according toclaim 1, wherein the lead body comprises a co-axial inner sheath andouter sheath and the braided coil is disposed between the inner sheathand the outer sheath.
 6. An extensible implantable electrical leadaccording to claim 1, wherein at least selected insulated electricalconductors have a rectangular cross-sectional profile.
 7. An extensibleimplantable electrical lead according to claim 1, wherein the polymericmaterial comprises silicone.
 8. An extensible implantable electricallead according to claim 1, wherein the plurality of electricalconductors is from four to sixteen electrical conductors.
 9. Anextensible implantable electrical lead according to claim 1, wherein thelead body further comprises a plurality of contacts at the distal end ofthe lead body and each electrical conductors connects a single distalend contact or electrode with a proximal end contact.
 10. An extensibleimplantable electrical lead according to claim 1, wherein the braidedcoil comprises two insulated electrical conductors for each braidelement.
 11. An implantable neurostimulation system comprising aneurostimulating device; and an extensible electrical lead electricallycoupled to the neurostimulating device, the extensible electrical leadelectrically comprising: a lead body having a proximal end and a distalend, the lead body formed of a polymeric material that is extensiblebetween a first length and a second length, the second length being 10%greater than the first length; and a plurality of electrical conductorsdisposed within the lead body and extending between the proximal end andthe distal end, the plurality of electrical conductors are eachelectrically insulated from each other and form a braided coil extendingbetween the proximal end and the distal end, the plurality of electricalconductors are electrically insulated and separated from each other andhave a first length braided coil diameter and a second length braidedcoil diameter being less than the first length braided coil diameter.12. An implantable neurostimulation system according to claim 11,wherein the extensible electrical lead is a lead extension thatelectrically couples the neurostimulating device to a proximal end of alead having a plurality of contacts at a distal end of the lead.
 13. Amethod comprising: applying a force of 5 N or less to a proximal end anda distal end of an extensible electrical lead having a first length, theforce increasing the first length of the extensible electrical lead byat least 10%, the electrical lead comprising: a lead body having aproximal end and a distal end, the lead body formed of a polymericmaterial that is extensible between a first length and a second length,the second length being 10% greater than the first length; and aplurality of electrical conductors disposed within the lead body andextending between the proximal end and the distal end, the plurality ofelectrical conductors are each electrically insulated from each otherand form a braided coil extending between the proximal end and thedistal end, the plurality of electrical conductors are electricallyinsulated and separated from each other and have a first length braidedcoil diameter and a second length braided coil diameter being less thanthe first length braided coil diameter; and removing the force from theextensible electrical lead to return the extensible electrical lead toits first length and the first length braided coil diameter.
 14. Amethod according to claim 13, wherein the applying step increases thefirst length by at least 20%.
 15. A method according to claim 13,wherein the applying step increases the first length by at least 25%.16. A method according to claim 13, further comprising implanting theextensible electrical lead in a patient.
 17. An extensible implantableelectrical lead according to claim 1, wherein a first plurality of theelectrical conductors are wound in a clockwise direction and a secondplurality of the electrical conductors are wound in a clockwisedirection and a third plurality the electrical conductors are wound in acounter clockwise direction and a fourth plurality of electricalconductors are wound in a counter clockwise direction.
 18. An extensibleimplantable electrical lead according to claim 1, wherein a first braidmember includes two electrical conductors that are insulated from eachother and are wound in a clockwise direction and a second braid memberincludes two electrical conductors that are insulated from each otherand are wound in a clockwise direction and a third braid member includestwo electrical conductors that are insulated from each other and arewound in a counter clockwise direction and a fourth braid memberincludes two electrical conductors that are insulated from each otherand are wound in a counter clockwise direction.
 19. An implantableneurostimulation system according to claim 11, wherein the braided coilcomprises two insulated electrical conductors for each braid element.20. A method according to claim 13, wherein the braided coil comprisestwo insulated electrical conductors for each braid element.